Method and apparatus for forming clips

ABSTRACT

U-SHAPED CLIPS OF THE TYPE EMPLOYED FOR SEALING SAUSAGE CASINGS, PLASTIC BAGS AND THE LIKE ARE FORMED WITH ARCUATE SURFACES ON THE EXTREMITIES OF THE OPPOSED LEGS FOR THE PURPOSE OF ENHANCING THE SEALING OPERATION WHEN THE CLIP TO BE SEALED. A NOTCHING AND SWAGING PUNCH IS APPLIED TO THE WIRE FROM WHICH THE CLIPS ARE FORMED TO PROVIDE ARCUATE SURFACES ON THE WIRE PRIOR TO CUTTING THE WIRE INTO THE LENGTHS FROM WHICH THE CLIPS ARE FORMED.

Oct. 12, 1971 K. A. KLENZ METHOD AND APPARATUS FOR FORMING CLIPS Filed Nov. 20,

l NVENT'O Z United States Patent ()1 hce 3,611,509 Patented Oct. 12, 1971 3,611,509 METHOD AND APPARATUS FOR FORMING CLIPS Karl A. Klenz, Oakland, Calif., assignor to Rheem Manufacturing Company, New York, N.Y. Continuation-impart of application Ser. No. 808,511, Mar. 19, 1969. This application Nov. 20, 1969, Ser. No. 878,437

Int. Cl. B21f 45/16; F16b /00 US. Cl. 2430.5 W 10 Claims ABSTRACT OF THE DISCLOSURE This application is a continuation-in-part of application Ser. No. 808,511, filed Mar. 19, 1969 and now Pat. No. 3,525,096, issued Aug. 18, 1970.

This invention relates to a method and apparatus for forming U-shaped clips of the type employed for tying flexible containers, such as plastic bags, sausage casings and the like. Such clips are deformed around the article to be sealed by urging the free ends of the opposed legs of the clip against a die having arcuate grooves so that the opposed legs are deformed and crossed over each other. This operation is disclosed in US. Pat. No. 3,400,433.

In the sealing operation performed by the clips of the type contemplated herein, a relatively high concentrated bearing stress results between the free ends of the clip legs and the deforming die which they engage. This high pressure tends to cause galling of the materials of the clip and die and results in reduced life of the latter. Furthermore, the friction between the clip legs and the die not only causes a loss of power but also impairs the sealing operation. In order to obviate these undesirable results, it has been proposed to apply wax or other antifriction material to the ends of the clips to reduce the force of friction resulting from the sealing operation. However, the concentrated pressures become so high in the clip deforming operation that such wax, when used, tends to be squeezed out of the area of engagement so that metal contact nevertheless results.

The main object of the present invention is to eliminate certain undesirable results heretofore attending the type of sealing operation shown in the above noted Pat. No. 3,400,433. This is accomplished by forming the free ends of the opposed legs of the clip so that a less intense concentrated pressure results between said free ends and the cooperating die.

Another object of the invention is the provision of a method and apparatus for preforming the ends of the legs of a U-shaped clip in a simple and inexpensive manner by modifying the shape of the wire from which the clips are formed. In this connection there is shown in US. patent application Ser. No. 808,511 a method of feeding and forming wire toward a clip forming operation and which method and apparatus may be the same as that employed for feeding and forming the clip wire of the instant invention. The step of modifying the wire shape in accordance with the present invention may be carried out at the cutoff block designated 26 in application Ser. No. 808,511.

Other objects and advantages of the present invention will be apparent from the following specification and from the drawings.

FIG. 1 is a semischematic top plan view of a portion of the length of wire being fed to the clip forming operation such as that shown in US. Ser. No. 808,511.

FIG. 2 is a transverse sectional view through the wire showing the notching and swaging punch.

FIG. 3 is a side elevation of the clip which is ultimately formed.

FIG. 4 is a schematic sectional view through the clip deforming die showing the engagement of the free end of a clip leg with the die groove.

In detail, and first with reference to FIG. 2, a cutoff block 26 is indicated which may be similar to the cutoif block indicated at 26 in the above noted pending application. Slidably supported for vertical reciprocation by suitable means (not shown) is a punch 10 which is adapted to reciprocate from an upper position clear of the wire 11 to a lower position at which the wire is partially cut and swaged. The wire 11 moves intermittently to the right in FIG. 1 as described in application Ser. No. 808,511 and the modified wire is shown at the right hand end of the figure.

Punch 10 is provided with a pair of spaced cutting edges 12, 13 from which the forming surfaces flare outwardly to both sides of said punch along arcuate surfaces as indicated. The inner end of the slot defined by the opposed cutting edges 12, 13 is rounded as best seen in FIG. 2 to provide arcuate surfaces 14 on both sides of the inner circular cutting edge 15. The contours of said surfaces 14 are preferably circular arcs.

As best seen in FIG. 2, the junctures 16 between the arcuate surfaces 14 and the opposite sides of the punch 10 almost approach the upper side of the wire 11 when the punch 10 is in its lowermost position indicated by dot-dash lines in FIG. 2. In this manner it will be apparent that the upwardly directed face of the wire 11 is formed to provide an arcuate surface 20 at each end of the length of wire from which the clip is formed (FIG. 1). :It will be understood that, as part of the subsequent clip forming operation, the wire 11 is cut by a shear (not shown) along the vertical planes indicated by lines 22 in FIG. 1.

The results of the above described operation is that a generally spherical surface is provided on the outer sides of the free ends of the legs 23, 24 of the completed clip generally designated 25 (FIG. 3).

With reference to the schematic drawing of FIG. 4, the portion of the die .30 first engaged by the legs 23, 24 is the bottom 25 of an arcuate groove 26. The generally spherical surface 20 of the clip legs engaging the groove 26 does so with a relatively large contact area so that the bearing pressure between the two surfaces is not sufficiently high to cause galling or, if the ends of the clips are waxed, the pressure is not sufiiciently high to cause the wax to be squeezed out of the area of engagement. Not only does this result in longer life of the die, but there is less likelihood of slivers of the clip material being deposited on the die. Such slivers are sometimes caused by the swaging action of the legs on the clip which causes the material of the clip to be wiped back to form a relatively thin section of clip material which may fall off and impair the clip forming operation.

Another advantage of the invention is that the reduction in friction between the clip legs and the die results in a smoother and tighter seal being formed around the article to which the clip is attached.

It will be understood that the surface 20 which engages the die 30 is toroidal in contour but in view of the relatively small area involved it may be considered to be substantially spherical or ball shaped.

In the foregoing description of a preferred embodiment, the invention has been disclosed as used on wire of generally trapezoidal cross sectional shape but it will be understood that the method and apparatus is unchanged when used on wire of circular cross section or other cross sections.

I claim:

1. The method of making a U-shaped clip having a pair of opposed legs from a length of wire comprising the steps of:

forming opposite ends of said length to provide arcuate convex die engaging surfaces,

bending said length to a U-shape with said convex surfaces directed oppositely outwardly of the free ends of said legs. 2. The method of claim 1 wherein said convex surfaces are formed by a swaging punch having generally toroidal forming surfaces.

3. The method of making a U-shaped clip from a length of wire comprising the steps of:

disposing an elongated wire horizontally, swaging the upwardly directed side of said wire at spaced points along its length to provide generally V-shaped upwardly Opening grooves with the opposed surfaces of each groove being of convex arcuate contour,

cutting through said wire centrally of said grooves to form a predetermined length of wire, and thereafter,

bending said length to form a U-shaped clip with the said arcuate surfaces directed oppositely outwardly at the free ends of the legs of said clip.

4. The method of claim 3 wherein said wire is partially cut through from the opposite lateral sides thereof substantially simultaneously with said swaging step.

5. The method of claim 4 wherein the cuts in said sides form grooves having opposed arcuate surfaces whereby the surfaces of the grooves formed by said swaging and cutting steps combine to form a substantially spherical end at said free ends of said legs.

'6. Apparatus for forming Wire comprising:

a cutting and swaging punch adapted to be reciprocated vertically toward and away from a length of wire and at right angles thereto,

said punch being formed with a slot having its opposite. sides formed with straight cutting edges spaced apart a distance less than the width of said wire and adapted to cut the opposite sides of said wire,

the inner end of said slot being formed to a semicircular cutting edge in continuation of said straight cutting edges and adapted to cut the topof said wire,

said slot being formed with opposite arouate surfaces diverging away from said straight and semicircular cutting edges toward the opposite sides of said punch,

whereby when said punch is urged downwardly against said wire said straight cutting edges partially 'cut through the width of said wire from the opposite sides thereof and the opposite arcuate surfaces swage said wire to form a groove extending along the sides and top of said wire with the opposed surfaces of said groove being substantially spherical segments.-

7. Apparatus according to claim 6 wherein said arcuate surfaces are of circular cross sectional contour.

8. A clip adapted for use in sealing a flexible container such as a sausage casing or the like comprising:

a length of wire bent to a generally U-shaped configuration and including a pair of opposedlegs connected together at their corresponding ends and being straight at their free ends opposite said connected ends,

the free ends of said legs being formed to provide arcuate surfaces directed oppositely outwardly of said ends.

9. A clip according to claim 8 wherein said arcuate surfaces are substantially spherical segments.

10. A clip according to claim -8 wherein said arcuate surfaces are formed by a punchhaving toroidal work forming surfaces.

References Cited UNITED STATES PATENTS 3,400,433 9/1968 Klenz 24-30.5 w 3,473,430 10/ 1969 Niedecker 49 FOREIGN PATENTS 875,459 5/1953 Germany 24-305 w DONALD A. GRIFFIN, Primary Examiner U.S. Cl. X.R. 8549; l40-82 

